Engine analyzers are known. Such devices, in the past, have typically been multifunction testers that could be interconnected with a number of functional areas of an engine for testing purposes. Often a single set of test leads were provided and functional areas of engines were tested one at a time with tester controls changed, as appropriate, to accommodate the test location.
Testing functions have included such parameters as ignition spark timing, battery voltage, and starter current. Other tested functions have included spark dwell, spark voltage, manifold vacuum, etc.
As engines have become more sophisticated, engine analyzers have also become more sophisticated. With increasing fuel prices and stricter emission controls, computers have become a necessary part of engine control systems. Engine analyzers, in order to troubleshoot computer controlled engine systems, have also become computer based.
With the recognition that automobiles are a major contributor to air pollution, automobile manufacturers of performance cars and otherwise have come to rely on computers as a means of controlling engine operating parameters while maximizing efficiency. Computers have been relied upon because of their almost infinite ability to adapt to a changing engine operating environment while optimizing engine operating parameters.
For example, it has long been known that a cold automobile engine requires a richer air-fuel mixture than a warm engine for proper operation. Even after an engine has reached a normal operating temperature, the air-fuel mixture must be constantly adjusted to changing load conditions. An idling engine, for example, need only be supplied with enough fuel to maintain an idle speed at 4 constant number of revolutions per minute (RPM), whereas an engine under load requires a much richer fuel mixture.
To improve combustion efficiency, fuel injection has been increasingly relied upon as a means of achieving an optimal air-fuel mixture across the full range of engine speeds and loads. In fuel injection systems, a precise volume of fuel is sprayed either directly into the combustion chamber or into the air stream during an intake period of each combustion cycle. The volume of fuel introduced during an injection cycle is usually controlled by a fuel injection control module based upon a throttle position.
The timing of the fuel injection is critical to good air-fuel mixing. If the timing of the injection is early or late the sprayed fuel simply condenses on the bottom of the intake manifold. The condensed fuel then enters the cylinders during subsequent intake cycles as a liquid instead of a vapor resulting in poor and incomplete combustion.
Another factor in ensuring complete combustion of the air-fuel mixture in the combustion chamber is the proper timing of a combustion spark. In the past, proper timing of the spark was controlled through a coil firing and spark distributing circuit (distributor) mechanically coupled to the engine camshaft. As a cylinder entered a combustion stroke, the mechanical movement of the camshaft positioned a rotor within the distributor towards a contact of a high voltage wire to the spark plug. At a pre-determined number of degrees before a piston within the combustion cylinder reached its upper-most position (top dead center (TDC)), an ignition control module associated with the distributor senses the position of distributor rotor shaft and applies a voltage pulse to an ignition coil firing the spark plug through the rotor and distributor.
Other ignition systems of more recent design (distributorless ignition systems) may provide an ignition coil for each pair of combustion cylinders while others provide a coil for each cylinder. A separate ignition module firing circuit is provided for each ignition coil. Such ignition systems do not have a distributor coupled to the camshaft for triggering a combustion spark through the coil and instead rely on solid state sensors (e.g., Hall effect sensors, magnetic pick-up coils, etc.) that are typically placed proximate the camshaft and crankshaft for detecting engine position. Such systems typically have a number of actuator structures (e.g., slots, cogs, pins, etc.) attached to the camshaft and crankshaft for activating the sensors, for proper firing of individual ignition modules.
The solid state sensors (crankshaft and camshaft) often provide signals to a control module that provides control for the generation of ignition and fuel injection control signals. Ignition and injector control, in fact, is often consolidated into a single engine control module (ECM).
While the consolidation of engine control functions into a small number of control modules has improved engine performance and reduced pollution, malfunctions have become harder to detect and resolve. Often, malfunctions are manifested in an intermittent manner or will only occur when an engine is under load (e.g., when a vehicle is accelerating). A technician must often resort to test drives in an effort to isolate and correct a problem. Unfortunately, where a vehicle is being driven, it is difficult to use sophisticated analyzers and test equipment as a means of isolating a source of a problem. Even where test equipment is portable and can be used in a moving vehicle, a second technician is usually required to operate the vehicle while the first technician operates the test equipment.
Technical training has also become a problem in the operation of the increasingly sophisticated test equipment that must be used with late model automobiles. Often a technician is as much a computer operator as troubleshooter. Even where a technician is proficient in computer operation, the interconnection of computer based test equipment with the automobile challenges the proficiency of even the most skilled technician.
Accordingly, it is an object of this invention to provide a method and an apparatus for testing motor vehicles that is portable and does not require a number of technicians to operate.
It is a further object of the invention to provide an apparatus that adapts to system abnormalities, either detected automatically by the apparatus or entered via a menu by a technician, as a means of detecting and quickly isolating faults
It is a further object of the invention to provide an apparatus for testing motor vehicles that is adaptable to a variety of models and manufacturers.
It is a further object of the invention to provide an apparatus that is as much a teaching tool as a troubleshooting tool.
It is a further object of the invention to provide an interactive troubleshooting tool that interacts both with the automobile being analyzed and with a remotely located instructor teaching a technician how to use the interactive troubleshooting tool.